While I have no explanation for the clustering, a yard is a long, long measure in football, with a dozen 4K cameras and a lot of very vested interests. Occasion

While I have no explanation for the clustering, a yard is a long, long measure in football, with a dozen 4K cameras and a lot of very vested interests. Occasionally spots seem generous or not, but that's to the measure of a couple of inches (e.g. he went down 4" short of the first down). As a long time fan it just doesn't seem reasonable to me that the ref opts for the 40 yard line instead of the 39 because there's a line. That's a 3 foot difference. To further support this, the bordering two yard counts do not depress the amount of the excess on the 5 yard marker. Not to mention that where the refs place the ball -- near the center of the field, usually on the left or right side depending upon where the play ended -- has a line on every yard marker. But again I have no explanation. We know that touchbacks start on the 20 or 25 yard line, and penalties are increments of 5 yards (e.g. face mask would be 15 yards, holding 10 yards, false start 5 yards, encroachment 5 yards, etc...and these can pile, kickoff out of the last five yards starts at the 40 yard line, etc), and to some degree this explains the 5 yard excess.